Spherical urea-aldehyde condensate fertilizers

Abstract

Fertilizers that contain urea-aldehyde condensates. The fertilizer can be spherical and can be formed using a granulation and/or spheronization technique and optionally can be an extruded fertilizer that is spheronized.

The invention claimed is: 
     
       1. A method for producing a spherical urea-C2-C4 aldehyde condensate fertilizer granule, the granule comprising a methylene urea and isobutylidenediurea, or a methylene urea and a derivative of isobutylidenediurea, the method comprising:
 (a) combining the methylene urea and the isobutylidenediurea or derivative of isobutylidenediurea and water to form a mixture; 
 (b) extruding the mixture; 
 (c) forming spheres from the mixture by spheronizing with a spheronizer; and 
 (d) drying the spheres to form the spherical urea-C2-C4 aldehyde condensate fertilizer granule, 
 wherein the spherical urea-C2-C4 aldehyde condensate fertilizer granule has an average crush strength of greater than 1.3 kgf/granule, and wherein the ratio of methylene urea to the isobutylidenediurea or the derivative of isobutylidenediurea is 75:25 to 50:50. 
 
     
     
       2. The method of  claim 1 , wherein the mixture is extruded through a perforated die before forming the spheres. 
     
     
       3. The method of  claim 1 , wherein the mixture is extruded by an extruder operated at a speed of 20 rpm to 300 rpm and a pressure of 1 bar to 50 bar. 
     
     
       4. The method of  claim 1 , wherein the spheronizer is operated at a disc speed of 1500 rpm to 5000 rpm and an air flow having pressure of 0.5 bar to 10 bar. 
     
     
       5. The method of  claim 1 , wherein the spheres have an average diameter of 1 mm to 3.5 mm. 
     
     
       6. The method of  claim 1 , wherein the mixture comprises 15 wt. % to 30 wt. % water. 
     
     
       7. The method of  claim 1 , wherein the mixture further comprises one or more flow promotors, binders, or a combination thereof. 
     
     
       8. The method of  claim 7 , wherein the flow promotor is one or more of bleached wheat flour, microcrystalline silica, chitosan, natural gums, gaur gum, clays, and cellulose derivatives. 
     
     
       9. The method of  claim 7 , wherein the binder is one or more of bleached wheat flour, gaur gum, calcium ligno sulfonate, gelatin, seaweed extract, plaster of paris, flour, starch, cellulose, gluten, colloidal silica, kaolin, bentonite, poly ethylene glycol, polycaprolactone, and low molecular weight poly vinyl acetate. 
     
     
       10. The method of  claim 1 , wherein the spherical urea-C2-C4 aldehyde condensate fertilizer granule has an average crush strength of greater than 1.6 kgf/granule. 
     
     
       11. The method of  claim 1 , wherein the spherical urea-C2-C4 aldehyde condensate fertilizer granule has an average diameter of 1 mm to 3.5 mm and an average crush strength of greater than 1.6 kgf/granule. 
     
     
       12. The method of  claim 1 , wherein the spherical urea-C2-C4 aldehyde condensate fertilizer granule has an average crush strength of greater than 2.0 kgf/granule. 
     
     
       13. The method of  claim 1 , wherein the spherical urea-C2-C4 aldehyde condensate fertilizer granule comprises less than 25 wt. % urea.